Interactions between spring wheat (Triticum aestivum ssp. vulgare L.) and undersown Persian clover (Trifolium resupinatum L.) depending on growth stage and plant density

Abstract

A pot experiment was conducted in the years 2010–2012. The competitive interactions between spring wheat and undersown Persian clover, depending on plant density have been established. The plants were grown in a mixture and in pure sowing at a higher density (according to the rules of proper agricultural practice) and at a density reduced by 20%. Based on measurements of dry matter in the aboveground parts and roots conducted at the wheat growth stages (BBCH) such as: leaf development (12–14), tillering (21–23), stem elongation (31–32), inflorescence emergence (54–56), and ripening (87–89), calculations of indicators such as: relative yield, relative yield total, competitive balance index and relative efficiency index, were performed. Competition between spring wheat and Persian clover continued from the wheat tillering stage until the end of vegetation. The strongest interactions were at the stem elongation stage (the plants competed for 95% of the growth factors), while at the end of vegetation the competition decreased slightly (it concerned 85% of the resources). The aboveground parts influenced one another with higher intensity than the roots. This was visible particularly well during the inflorescence emergence stage, during which the plants accumulated only 8% of the resources in the aboveground parts, while 89% was accumulated in the roots. Wheat proved to be the stronger competitor for the growth factors. It reduced by more than twice the increase in the biomass of Persian clover from tillering until the end of vegetation. In the mixture, the relative growth rate of the aboveground parts of clover was higher than in the case of wheat, while the growth rate of the roots was similar for both species. Plant density had no significant impact on the intensity of mutual interactions.